From: Goldwyn Rodrigues rgoldwyn@suse.com
commit 9cf35f673583ccc9f3e2507498b3079d56614ad3 upstream.
This is similar to 942491c9e6d6 ("xfs: fix AIM7 regression"). Apparently our current rwsem code doesn't like doing the trylock, then lock for real scheme. This causes extra contention on the lock and can be measured eg. by AIM7 benchmark. So change our read/write methods to just do the trylock for the RWF_NOWAIT case.
Fixes: edf064e7c6fe ("btrfs: nowait aio support") Signed-off-by: Goldwyn Rodrigues rgoldwyn@suse.com Reviewed-by: David Sterba dsterba@suse.com [ update changelog ] Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/btrfs/file.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1890,9 +1890,10 @@ static ssize_t btrfs_file_write_iter(str (iocb->ki_flags & IOCB_NOWAIT)) return -EOPNOTSUPP;
- if (!inode_trylock(inode)) { - if (iocb->ki_flags & IOCB_NOWAIT) + if (iocb->ki_flags & IOCB_NOWAIT) { + if (!inode_trylock(inode)) return -EAGAIN; + } else { inode_lock(inode); }